Efficacy and Safety of Plecanatide in Children 6 to <18 Years of Age With Irritable Bowel Syndrome With Constipation (IBS-C)

The purpose of this study is to evaluate the safety, efficacy and pharmacokinetic (PK)
parameters of plecanatide of once daily oral 4 dose levels of plecanatide (0.5, 1.0, 2.0, or
3.0 mg) for 4 weeks as treatment in children 6 to <18 years of age with IBS-C.

The study will include a 28-day Screening/Baseline Period, a 4 week treatment period, and a
2-week post-treatment follow-up period. Patients/caregivers will visit the clinic 4 times
during the study.

INCLUSION CRITERIA

A patient will be eligible for study participation if he or she meets all of the following
criteria:

1. Male or female child aged 6 to < 18;

2. Meets ROME IV criteria for child/adolescent IBS-C

3. Patient's parent/guardian/LAR is able to voluntarily provide written, signed, and
dated consent and patient is able to voluntarily provide assent as per IRB guidance;

4. Patient and patient's parent/guardian/LAR demonstrates an understanding, ability, and
willingness to fully comply with study procedures

EXCLUSION CRITERIA

A patient will be excluded from the study if he or she meets any of the following criteria:

1. The patient has a mental age <4 years in the investigator's opinion;

2. The patient has previously been diagnosed with anorectal malformations, neurological
deficits, or anatomical anomalies that would constitute a predisposition to
constipation;

3. The patient is pregnant or lactating;

4. The patient's mobility or normal exercise tolerance is compromised in the
investigator's opinion;

5. The patient has been screened for or participated in another Synergy study in the
past;

6. The patient has a sibling that is currently participating or has participated in
another Synergy study.